From the previous volume (Assassination Classroom Vol. 11), Karasuma provides the students with a new set of clothes which more suitable for assassination work. At the same time, a legendary hitman appears and targeting someone in the school.
Irina's birthday has just passed and she is hoping to get a birthday present from Karusuma. The students is getting a birthday gift on behalf of Karasuma-sensei. Karasuma-sensei just passes the gift to her, without any knowledge of Irina's feelings to him.
The world's best hitman, "God of Death" is here. His assassination and disguise skills are elite level. Several hitmen have been killed recently. Coincidentally, Irina-sensei has been missing several days. An unexpected guest reveals Irina-sensei's location but the students have to gather themselves together at a specified place to save her.
The remaining story in this volume will be the battle against the "God of Death". Worse, they need to fight with Irina-sensei as well. What leads to Irina-sensei's betrayal? Will Karasuma-sensei able to defeat the "God of Death" and saves the students?
My only words for this volume - Any girls will fall in love with Karasuma-sensei. Well, I always attracted by his coolness and he does have a good look but this volume really proves that he's flawless.
More reviews can be found on Goodreads: Assassination Classroom, Vol. 12: Shinigami Time (Assassination Classroom #12).